During flight, helicopter rotor blades produce significant vibration and noise as a result of variations in rotor blade aerodynamic loads with blade azimuth angle. On this reason future helicopters need to be improved with respect to environmental and public acceptance. Significant vibration and noise reduction can be achieved without the need for complex mechanisms in the rotating system using active twist control of helicopter rotor blades by an application of MFC actuators. In this case MFC actuators are implemented in the form of active plies within the composite skin of the rotor blade with orientation at 450 to the blade axis to maximize the shear deformations in the laminated skin producing a distributed twisting moment along the blade. The present investigations are devoted to the methodology development for the optimal design of active rotor blades using MFC actuators to obtain high piezoelectric actuation forces and displacements with a minimum actuator weight. A number of theoretical and experimental studies have been performed to estimate an active twist of helicopter rotor blades required to effect noise and vibration reduction benefits, as well as to improve the overall performances of helicopters [1-3]. The objective of the present study is development of the methodology, based on the planning of experiments and response surface technique, for the optimal design of active rotor blades using MFC actuators to obtain high piezoelectric actuation forces and displacements with minimal actuator weight and energy applied. 3D structural static analysis with thermal load is carried out to characterise an active twist of the helicopter rotor blade. The full scale helicopter rotor blade consists of C-spar made of uni-directional GFRP, skin made from +450/-450 GFRP, foam core, MFC actuators embedded into the skin, balance weight and root. To investigate an active twist of the helicopter rotor blade, the steady-state thermal analysis using 3D finite element model has been developed. In this case thermal strain analogy between piezoelectric strains and thermally induced strains is used to model piezoelectric effects. 3D finite element model of the full scale helicopter rotor blade has been built by ANSYS, where the rotor blade skin, spar “moustaches” and root are modelled by the linear layered structural shell elements SHELL99, and the spar and foam - by 3D 20-node structural solid elements SOLID186. The node-offset option is applied for the joint skin-spar “moustaches” structure with a location of the finite element nodes at the top surface to preserve the rotor blade profile. An optimisation problem for the optimum placement of actuators in the full scale helicopter rotor blades has been formulated on the results of parametric study of model scale helicopter rotor blades using the finite element method. Due to a large dimension of the numerical problem to be solved, an optimisation methodology is developed employing the method of experimental design and response surface technique. The points of experiments in the domain of factors are distributed as regular as possible. In the present approach a form of the equation of regression is unknown previously. Synthesis of the equation from the bank of simple functions is carried out in two steps: selection of perspective functions from the bank and then step-by-step elimination of the selected functions. In the first step all variants are tested with the least square method and the function, which leads to the minimum of the sum of deviations, is chosen for each variant. In the second step the elimination is carried out using the standard deviation or correlation coefficient. During flight, helicopter rotor blades produce significant vibration and noise as a result of variations in rotor blade aerodynamic loads with blade azimuth angle. On this reason future helicopters need to be improved with respect to environmental and public acceptance. Significant vibration and noise reduction can be achieved without the need for complex mechanisms in the rotating system using active twist control of helicopter rotor blades by an application of MFC actuators. In this case MFC actuators are implemented in the form of active plies within the composite skin of the rotor blade with orientation at 450 to the blade axis to maximize the shear deformations in the laminated skin producing a distributed twisting moment along the blade. The present investigations are devoted to the methodology development for the optimal design of active rotor blades using MFC actuators to obtain high piezoelectric actuation forces and displacements with a minimum actuator weight. A number of theoretical and experimental studies have been performed to estimate an active twist of helicopter rotor blades required to effect noise and vibration reduction benefits, as well as to improve the overall performances of helicopters [1-3]. The objective of the present study is development of the methodology, based on the planning of experiments and response surface technique, for the optimal design of active rotor blades using MFC actuators to obtain high piezoelectric actuation forces and displacements with minimal actuator weight and energy applied. 3D structural static analysis with thermal load is carried out to characterise an active twist of the helicopter rotor blade.